The present invention relates to pollution control apparatuses and methods for reducing contaminants in an effluent gas flow, and more particularly to pollution control devices utilizing non-thermal plasma reactors.
Today""s industrial processes create enormous amounts of pollutants. Many of these sources release gases containing these pollutants into the environment. Examples of these sources include factories, combustion engines, dump sites, land fills, sewage treatment plants and lagoons and waste heaps, to name a few. The primary air pollutants in these gases include NO, NO2, SO2, CO2, and hydrocarbons.
Several devices and methods for removing pollutants from these gases have developed. These devices utilize mechanical, electrical, electrochemical, and chemical processes. Typical examples include filters, aqueous scrubbers, electrostatic precipitators, and catalytic converters.
Some existing electrical and electrochemical pollution control devices and methods operate on the theory that through dissociation, toxic and hazardous oxides can be separated from an effluent gas through ionization and non-thermal plasma fields. One such pollution control device is described in U.S. Pat. No. 5,366,701 issued to Taylor et al. on Nov. 22, 1994, the entirety of which is hereby incorporated by reference.
Taylor describes an apparatus where an effluent gas is ionized in a resonance field and then passed through a continuous electric arc to potentialize the gas. The treated effluent gas is then released into the environment at temperatures ranging from 100xc2x0 F. to 250xc2x0 F. where ultraviolet light and the solar spectrum ideally energize the gas into inert non-toxic gases. Unfortunately, processes such as the one disclosed in Taylor do not complete the processing of dissociated contaminants, such as dissociated oxides. Although the temperature of the released effluent gas is lower than the temperature of the effluent gas entering the apparatus, the release temperature of the gas is still elevated. Therefore, the gas is still in an excited state and re-association of excited radical oxides is prevalent, for example, thereby allowing the formation of harmful pollutants that include aerosol chains that lead to greenhouse gases and acid rain.
Still further, some pollution control devices utilize non-thermal plasma reactors that expose an electrode, such as a corona wire, to the contaminants in the effluent gas to be treated. Contaminants accumulate on the electrode and reduce the efficiency of the device. The electrode eventually must be replaced.
Therefore, there remains a need to process effluent gases in a manner that substantially reduces the re-association of dissociated components of an effluent gas into harmful pollutants, particularly as environmental regulations become increasingly more stringent. Also, there remains a need for a pollution control device which allows for recapture of commercially valuable products. Further, there remains a need for a new non-thermal plasma reactor that efficiently processes contaminants in an effluent gas without exposing the electrode to harmful contaminants.
A pollution control device for reducing contaminants in an effluent gas includes a resonance chamber in gaseous communication with a source of the effluent gas. The resonance chamber ionizes the effluent gas. An output non-thermal plasma reactor is in gaseous communication with an output of the resonance chamber and destroys at least a portion of the contaminants in the effluent gas. The pollution control device also includes an output cooling unit in gaseous communication with an output of the output non-thermal plasma reactor. The output cooling unit is adapted to cool the effluent gas to a non-excited state, whereby re-association of oxides in the effluent gas is substantially reduced.
The pollution control device provides several benefits over existing pollution control devices. For example, the processed effluent gas is placed in a steady state prior to either release into the environment or re-injection into the source of the effluent gas. It is believed that the steady state effluent gas tends to associate into near perfect molecules rather than re-associate into harmful pollutants, thereby preventing the formation of harmful pollutants that include aerosol chains that lead to greenhouse gases and acid rain. Also, the cooling of the effluent gas may cause the effluent gas to reach several dew points within the pollution control device. These dew points allow for the recovery of commercially significant compounds, such as sulfates, sulfites, nitrates, and nitrites.
The above and other features of the present invention will be better understood from the following detailed description of the preferred embodiments of the invention that is provided in connection with the accompanying drawings.